The present invention relates to a vehicle suspension, and more particularly to a car suspension incorporating helical springs.
Vehicle suspensions, particularly automobile suspensions, using helical compression springs are already known and in wide-spread use. The utilization of the vehicle springs in vehicle suspensions has brought about many advantages. More particularly, such suspensions are less complex, more reliable and easier to maintain and repair during the lifetime of the vehicle than other suspensions. Also, such suspensions result in a more comfortable ride for the driver and the passengers of the vehicle, particularly due to the greater elasticity and compressibility of the helical springs as compared to those obtainable by using leaf springs. While such suspensions using helical springs have initially been used only for suspending the front wheels of vehicles, the use of such springs has spread in the last year also to the rear wheels of the vehicles.
As advantageous as such suspensions may be, particularly for ride on well-paved roads, they also have serious drawbacks, particularly when the vehicle is driven over roads of inferior quality. A matter of particular concern is that the higher compressibility or elasticity of the helical springs used in such present-day suspensions may result in a situation where the automobile travelling over roads of inferior quality may conduct excessive lateral or front-to-rear movements when the wheels of the vehicle come into contact with irregularities of the surface of the road. This is particularly true when the surface of the road has a wavy configuration which can result from erosion of the pavement due to weather influences or due to the passage of many and/or heavy vehicles over the road. Such movements of the car are not only very uncomfortable to the driver and the passengers of the automobile, but can also result in an impairment or a partial loss of control over the vehicle. Therefore, in order to avoid such excessive movements, the car must be driven on inferior-quality roads at very low speeds. However, even at slow speeds the ride in a car equipped with such a suspension is rather uncomfortable due to the frequent and substantial movements of the car in various directions. A way of avoiding this disadvantage would be to either permanently stiffen the helical springs or to replace them by other springs having a lower degree of compressibility. However, these expedients would result in a less comfortable ride not only over inferior roads, but also over superior roads.